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Three car seats, including Keyfit 30, in rear of Gen 3 Prius (2010)

I found two older posts on the topic, but they were from 2009 and 2011, so I thought I'd ask here again in 2019. I've got a 2010 Toyota Prius (not the c or the V), and we have our third child arriving in February 2020.

Rather than buying a new car, i.e., an SUV or mini-van, we would prefer to hold onto the Prius. For the infant, we have the Chicco Keyfit 30. For our two older kids (they will be 6 and 3 when the baby is born), are in a Diono Rainier and a Britax Pavilion 70-G3, respectively (both will be front-facing). We also own a second Diono Rainier, along with a Radian RXT, both of which are in my wife's car.

Bottom line is this - I'd like to fit three car seats in the Prius, one of which must be the Keyfit 30, with its base. Can I accomplish this with two Radians - the Radian RXT from my wife's car, plus a new Radian (whether the 3R, 3RX, RXT JMC, or the 3RXT) - or are there other front-facing convertibles/harnessed boosters you'd recommend? For example, one that came up in my searches was the Graco Tranzitions. I am not set on having an all-Diono setup, so I am open to recommendations/thoughts.

Since you already have the Dionos, I would start by trying them. I am envisioning that if you install the Dionos on either side with the seat belts, you should have room for the KeyFit base in the center. Since the Dionos are very low-profile, the widest part of the KeyFit carrier may not touch them.

I know others have had more direct experience with this vehicle, so hopefully they will chime in too. Basically, see if you can do it, trying every possible combination if the first doesn't work. If not, or if so, let us know!

-Reta
Former CPST
Mom of V, born 6/2014, FF in a Pioneer, Boulevard G4, and SureRide
G dog, rescued 6/2016, in a belted SturdiBag

The Prius is difficult for 3-across, as are most compact cars. Likely there is a combination that will work according to instructions, but may not meet other best practice guidelines about "crossover" of seatbelts or puzzling of adjacent seats. Fortunately, these aren't actually rules unless they are indicated in an owner's manual or state law, so sometimes you can still get an adequately tight install of 3 seats in back with trial and error. My best suggestion is to also visit a local certified technician for any 3-across setup in a small car unless you are confident enough to keep trying on your own.

I would be reluctant to suggest a new Radian if you have one already. It's not a good value especially for a 6-year old. For a typical child age 6, a narrow backless booster may be a good solution along with a narrow harnessed seat for your 3-year old and your Keyfit for the baby. Congratulations in advance!

Since you already have the Dionos, I would start by trying them. I am envisioning that if you install the Dionos on either side with the seat belts, you should have room for the KeyFit base in the center. Since the Dionos are very low-profile, the widest part of the KeyFit carrier may not touch them.

I know others have had more direct experience with this vehicle, so hopefully they will chime in too. Basically, see if you can do it, trying every possible combination if the first doesn't work. If not, or if so, let us know!

Originally Posted by SafeDad

The Prius is difficult for 3-across, as are most compact cars. Likely there is a combination that will work according to instructions, but may not meet other best practice guidelines about "crossover" of seatbelts or puzzling of adjacent seats. Fortunately, these aren't actually rules unless they are indicated in an owner's manual or state law, so sometimes you can still get an adequately tight install of 3 seats in back with trial and error. My best suggestion is to also visit a local certified technician for any 3-across setup in a small car unless you are confident enough to keep trying on your own.

I would be reluctant to suggest a new Radian if you have one already. It's not a good value especially for a 6-year old. For a typical child age 6, a narrow backless booster may be a good solution along with a narrow harnessed seat for your 3-year old and your Keyfit for the baby. Congratulations in advance!

Thank you for the input. We've got a few months until the arrival of the baby, but I will try the Radian, a backless booster, and the Chicco. If that does not work, do you have any suggestions for a narrow harnessed seat, e.g., a harnessed booster that can preferably be converted into a high back booster and a backless booster?

@MelodyoftheForest - had not considered putting the Chicco in the middle seat. I figured it would be easiest getting the baby in and out of the car if s/he was placed behind the passenger.

The 3 narrowest harness-to-booster seats are the Chicco MyFit (http://amzn.to/2BDq8aG), the Graco Tranzitions (http://amzn.to/2uvnIJy), and the Harmony Defender. They all have installation challenges, but the Defender is like the Ikea carseat since it has to be put together with tools (not difficult, but still . . .). Whatever you decide to try, be sure to buy from a place that has a good return policy in case you need to return the seat.

The 3 narrowest harness-to-booster seats are the Chicco MyFit (http://amzn.to/2BDq8aG), the Graco Tranzitions (http://amzn.to/2uvnIJy), and the Harmony Defender. They all have installation challenges, but the Defender is like the Ikea carseat since it has to be put together with tools (not difficult, but still . . .). Whatever you decide to try, be sure to buy from a place that has a good return policy in case you need to return the seat.

The 3 narrowest harness-to-booster seats are the Chicco MyFit (http://amzn.to/2BDq8aG), the Graco Tranzitions (http://amzn.to/2uvnIJy), and the Harmony Defender. They all have installation challenges, but the Defender is like the Ikea carseat since it has to be put together with tools (not difficult, but still . . .). Whatever you decide to try, be sure to buy from a place that has a good return policy in case you need to return the seat.

Thank you. One thing I did not ask in my original post, but what are your thoughts on a backless booster v. a harnessed booster/belt booster? Our (almost) six-year old is about 45 pounds and tall (don't remember his exact height), and we have a Graco Turbobooster that we recently purchased for vacations.

Our son is tall and heavy enough for the backless booster, but I wonder if it is inadvisable to have him sit in it as his "regular" carseat. However - the Prius would be the backup pickup/dropoff vehicle, and trips with all three kids would rarely be for more than . 30 minutes at a time. If we took longer trips, it would be in my wife's SUV, where we have confirmed we can get 2 Dionos and the Chicco Keyfit all in one row (and we have a third row if we need to move one or more of the kids back there).

I imagine a backless booster will take up less real estate than even the Tranzitions, Myfit or Defender, but I also imagine a harnessed or belt booster will be safer than a backless booster. However, if I were to use a backless booster, the idea is that I'd put our 6-year old in the middle seat, and have our 3-year old behind the driver (in one of the Dionos), and have the infant behind the passenger in the Chicco Keyfit 30.

As an alternative to any of the foregoing options, what are people's thoughts about the Ridesafer Vest?

There is virtually no data available to compare the safety of a backless or high back boosters to a harnessed carseat for a typical child above 4 years old. Your arrangement of having the child in the backless booster in the middle is a good option to start. If the belt fit is an issue, you may have to switch.

Note that the Graco Turbobooster can be used as a backless booster. It's not the narrowest one available, but it's pretty simple to remove the back if the back is a conflict with an adjacent seat. Based on my experience, the vast majority of 6-year olds are in boosters, with backless probably being more common at that age.

There is virtually no data available to compare the safety of a backless or high back boosters to a harnessed carseat for a typical child above 4 years old. Your arrangement of having the child in the backless booster in the middle is a good option to start. If the belt fit is an issue, you may have to switch.

Note that the Graco Turbobooster can be used as a backless booster. It's not the narrowest one available, but it's pretty simple to remove the back if the back is a conflict with an adjacent seat. Based on my experience, the vast majority of 6-year olds are in boosters, with backless probably being more common at that age.

I was skeptical, but I think I was able to get three car seats in the back of my 2010 Prius (although I may need to re-do the install to make sure the seats are level). I've got a Diono Rainier behind the driver, the Chicco Keyfit 30 in the middle seat (with the base), and some random 2-in-1 booster (which my sister in law had sitting in her house) behind the passenger (all three are secured with the seatbelt). I've got to wash the cover on the 2-in-1 booster anyway, so I'll try to figure out what make and model it is. I also confirmed I was able to install and remove the Chicco from its base, even with seats on either side

I didn't think to try putting the Chicco behind the passenger seat, although I think this setup may actually work better, since the infant won't be in my car that often, meaning the two older kids won't have to sit next to each other all the time.

With the backless booster, while I confirmed that would have worked w/ the Rainier and the Keyfit 30, my concern was that it would be a challenge for our nearly six-year old to strap his seatbelt into the seatbelt stalk/buckle, unless I invested in one of those buckle holders that are sold on Amazon. I think using two harnessed car seats would make everyone's life a bit easier.

The mystery seat looks like a Cosco Highback, which is outgrown early. Check the fit, and remember that the straps should come from at or above shoulder height since it’s a forward facing restraint. If it is outgrown (or expired, check for that when you look over the seat), a Cosco Finale is a similar size and might work in its place.

The mystery seat looks like a Cosco Highback, which is outgrown early. Check the fit, and remember that the straps should come from at or above shoulder height since it’s a forward facing restraint. If it is outgrown (or expired, check for that when you look over the seat), a Cosco Finale is a similar size and might work in its place.

@jjordan - I think you're right. I do remember the seat having a Cosco instruction manual, but I could not recall the model name (thought it was the Highback but did not want to say so unless I was sure). Also, if I am remembering correctly, it had a manufacture date of 2016, so it should not be expired yet.

I checked the Cosco with our almost three-year old, and it definitely fits her, and I was able to get a tight install of the car seat.

However, after showing this to my wife, she's skeptical of using the Cosco, since, in her mind, it does not look as substantial as our other car seats, i.e., she questions whether it would be safe for our younger child, so I may take one of the two Dionos from her car, and put the Britax Pavilion 70-G3 (which is what I had in the Prius for our younger child before I removed it to try a three-seat install) in her SUV. Even with the Britax in her car, the Keyfit should still fit in the same row.

Got a question - the Cosco Highback is advertised as a 2-in-1 booster, but is a harnessed booster the same thing as a front-facing car seat? When I told my wife I had put a harnessed booster in the Prius, she expressed concern whether a harnessed booster would be appropriate and safe for our younger child, even though she is within the height and weight limits for the seat (admittedly, her concern was also because the Cosco is a plastic frame with minimal padding, whereas the Diono is a much more substantial, and much more cushioned, car seat).

Based on my very limited understanding, a harnessed booster is the same as a front-facing convertible since, in both situations, the kid is secured by a five-point harness, and the car seat is attached to the car by a latch/seatbelt, with a tether. In addition, since all car seats have to pass the same safety tests, a $50 Cosco would be safe for our child, just as a $200+ Diono would be. However, please correct me if any of my understanding here is wrong.

You are correct, a forward facing harness is just that regardless if it is marketed as a harnessed booster or a convertible or some other name. And all seats sold in the US need to meet the same federal safety standards, whether a $50 Cosco or $250 Diono or $500 Clek. Technically we can’t say they’re all equally safe, because quite possibly one seat might protect better than another in any given crash scenario. But the truth is that we can’t definitively say which seat would be better, not to mention seat A might be best in crash scenario X and seat B in crash scenario Y and so on. So the “which is safest” question is a tricky one. (I usually tell people that if they see a certain feature that they think will make their child safer, and if they want to spend the money to get that feature, then go for it, but don’t feel bad if you can’t or don’t want to spend more than you have to.) All that said - 3 across in a Prius isn’t going to give you a lot of options so take what you can get!

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